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| Home > Publications database > Gitterdynamik von Imidazol |
| Book/Report | FZJ-2018-02274 |
1983
Kernforschungsanlage Jülich, Verlag
Jülich
Please use a persistent id in citations: http://hdl.handle.net/2128/17961
Report No.: Juel-1850
Abstract: The lattice dynamics of imidazole have been investigated. To this end dispersion curves have been determined at 10 K by inelastic coherent neutron scattering. Strictly speaking, of the 24 expected external curves 22 were measured along the symmetry directions (100) and (001) and ten branches along (010). RAMAN measurements have been done to investigate $\lceil$ - point modes. The combination of extinction rules for RAMAN - and neutron scattering leads to the symmetry assignment of $\lceil$- point modes. The experiment yields a force constant of the streching vibration of the hydrogen bond of 0.33 mdyn/A. A force model has been developed to describe the intermolecular atom - atom interactions in imidazole. In a minimisation routine the open parameters of the force model have been fitted to the observed dispersion branches. The force model contains the van der Waals -, the exchange interaction and the interactions of static monopoles and dipoles. These static multipoles take into account the differences of the electronegativities within the molecule and its asymmetric shape. An essential part of the hydrogen bond is provided by the static multipole interaction.
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